Along with the popularization of terminal equipment such as smart phones, users have more and more diversified requirements on functions of terminal equipment. For example, a camera function of terminal equipment may bring great convenience to production and life of users and thus is widely needed by the users. A key to guarantee quality of an image shot by a camera lies in exposure control. Exposure control aims to reduce overexposed and underexposed regions in an image as much as possible, meanwhile luminance of the present image is ensured to be consistent with expected luminance.
In a related technology, an AEC technology is adopted to control a sensor and Image Signal Processor (ISP) of a camera to perform overall exposure control over an image, thereby automatically obtaining reasonable image luminance.
However, in the AEC technology, a mainstream AEC algorithm controls image luminance based on luminance information of a whole frame of an image. When a portrait is shot, if a difference between luminance of a region of interest and luminance of a region around the region of interest is relatively large, such a manner of performing exposure control based on average luminance may easily make the region of interest overexposed. Overexposure of an image may make information unrecoverable and reduce quality of the shot image.